Possible Spin Triplet Superconductivity inNaxCoO2·yH2O

Symmetry-based considerations are combined with inputs from available experimental results to make the case that a novel spin-triplet superconductivity triggered by antiferromagnetic fluctuations may be realized in the newly discovered layered cobaltide ${\mathrm{N}\mathrm{a}}_x{\mathrm{C}\mathrm{o}\mathrm{O}}_2·y{\mathrm{H}}_2\mathrm{O}$. In the proposed picture, inaccessible via resonating-valence-bond physics extrapolated from half-filling, the pairing process is similar to that advanced for ${\mathrm{S}\mathrm{r}}_2{\mathrm{R}\mathrm{u}\mathrm{O}}_4$, but enjoys a further advantage coming from the hexagonal structure of the Fermi surface which gives a stronger pairing tendency.